| 摘要 |
PROBLEM TO BE SOLVED: To obtain a welded joining plate excellent in a press-formability at the time of forming by applying a tailored blank technique by specifying the values of yield stresses and plate thicknesses of the joining steel plates. SOLUTION: The product of the yield stress YS and the plate thickness (t) in the joining steel plates, is made to (YS×t) and the difference of the products is made toΔ(YS×t). The metallic plates are combined so that the differenceΔ(YS×t) becomes <=20% of the larger part in the product (YS×t) of the steel plate. In the adjacent metallic plate interposing a welding line, the one side is made to the metal having <=320 MPa yield stress and <=450 MPa tensile strength and the other side is made to the metal having <=320 MPa yield stress and <=550 MPa tensile strength. In the adjacent metallic plate interposing the welding line, at least one side is made to the steel plate containing by wt.% of 0.001-0.2 C, 0.005-1.5 Si, 0.05-3.5 Mn, 0.005-0.15 P, <=0.02 S, 0.005-0.2 Al, <=0.02 N and the balance substantially Fe.
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